The European patent application EP0344293B1 discusses a nuclear magnetic resonance signal acquisition apparatus that includes a coil, a matching means and a preamplifier. The coil has a source impedance (designated Rs in the aforementioned European patent application), while the preamplifier has an optimum source impedance Ropt and an input impedance Rin, with Rin being less than Ropt. The matching means connects the coil to the preamplifier such that the source impedance of the coil Rs is transformed by the matching means to be approximately equal to the optimum source impedance Ropt at the point of connection between the matching means and the preamplifier. At the same time, the low input impedance of the preamplifier is transformed by the matching means to be a value higher than the optimum source impedance Ropt at the point of connection between the matching means and the coil.